Method of separating and fractionating oil



Patented Oct. 25, 1932 UNITED STATES PATENT orr ca GARY R WAGNER, OFCHICAGO, ILLINOIS, ASSIGNOB '10 'rrmem P300388 COMPANY,

OF DE'I BOIT, MIG HIGAN, A CORPORATION OF IIGBIGAI METHOD OI SEPABATINGAND FRACTIONATIHG 0111 1 y Application filed march 1:, 192a. Serial No.281,410.

This invention relates to an im roved method ofheating, fractionating anse arating the 'condensible and non-condensi 1e hydrocarbon vapors orfluids which are released from the conversion zones of oil crackmgsystems.

The present invention is particularly applicable to vapor phase or hightemperature methods of oil conversion, wherein oil to be cracked isheated to a vaporous state and then admixed with steam and the resultingmixture of steam and oil vapor passed through a zone of high temperaturefor the purpose of effecting the molecular decomposition or w crackingof the oil vapor. After the vapors have been subjected to the high heatregion for a period of time sufiicient to produce the desired degree ofcracking, the vapors are cooled and are then transferred to separating59 or fractionating apparatus in which the several fractions of thevapors having diii'erent hailing points are relativeiy separated andcondensed, provision being made for the removal in a separated conditionof the fixed g gases and. the water content resulting from the use ofsteam and it is particularly to the separation or fractionation of thesefluids and the treating thereof to remove certain undesirable compoundsthat the present inso vention is directed.

in the operation of certain vapor phase systems or oil conversion it hasbeen found desirable, in order to remove compounds from the oil whichtend todiscolor the same and which form gum deposits therein, to passthe oil vapors obtained irom a cracking still through a tower containinga body of filtering material in the form of iullers earth. Hitherto ithas been customary to pass oil vapor, fixed gases, steam or waterdirectly from the converter through the fullers earth tower. This methodhas been found to be unsatisfactory for the reason that the iullersearth is required to handle an immense amount of material which does notrequire such treatment, with the result that the 111- lers earth rapidlyloses its value as a filtering or purifyin material sothat frequent reasplacement t ereof with fresh iuilers earth has been necessary to keepthesystem in its most efiicient operative condition.

In accordance with the present invention a method is provided wherebythe undesired oils, fixed gas, steam or water are removed from the oilvapors or liquids which require treatment with the fuller s earth, sothat the quantity of oil and oil vapors passing through a given bod offullers earth will be more effectively an efiiciently filtered than hasbeen accomplished in the past, for the reason that the extraneous orunnecessary materials are first removed and only that portion of thecracked stock which requires filtration is passed through the fullersearth. Another advantage resides in the fact that oil vapors which arepassed throu h the fullers earth bed may be maintaine at a considerablyhigher temperature than when mixed with the undesirable compounds. Thisenables the fullers earth to react with the oil vapors to betteradvantage in effecting a more complete removal of the undesirable colorand gum formin compounds.

I do not limit mysel to the use of fullers earth alone in the treatmentof the oil va ors for the purpose of improving color an removingpolymers, since the invention is also applicable to other materials andmethods such as the treatment of the oil vapors with mild sulphuric acidcompounds.

In the accompanying drawing there has been disclosed diagrammaticallyapparatus for carrying out the present invention in one of its preferredforms.

Referring more particularly to the drawing the numeral 1 designates thesetting of an oil heater or converter. Within this setting there ispositioned a bank of oil converting tubes 2 through which is ada ted topass a current of oil vapor in or er that such vapor may he subjected tothe internal heat of the furnace and its temperature raised sufficientlyto eflect the desired conversion reactions. The oil enters the tubes byway of the pipe line 3 and, if desired, superheated may be mixed withthese oil vapors by being introduced into the line 3 as indlcated at 4.The temperature of the oil vapor within the converter is raised to apoint in excess of NOW 100 F., while the vapors are maintained under apressure not in excess of two atmospheres. It will be understood,however, that I do not limit myself to these precise temperatures orpressures, since the present invention is applicable to any vapor phasemethod of oil conversion.

When the vapors leave the outlet 4 of the tube bank 2, the same aredischarged into a jet condenser 5 into which is forced fresh cool oil byway of the pi line 6 from the storage tank'7. The hea oil va ors issuingfrom the converter are shock chill V intimate contact with the coolcharging stock so that conversion reactions are checked and the oilvapor sufliciently lowered in temperature so that the heavier endsthereof will condense in the bottom of the condenser 5 and are thereintermingled with the fresh charging stock, which has not been vaporizedby a contact with the heated vapors. The liquid in the bottom of thecondenser 5 is transferred by means of a pipe line 8 to the bottom of afractionating tower 9, while the vapors or gases are drawn of! from thetop of the jet condenser by way of a pipe line 10 and are led to theinterior of the fractionating tower 9 at a position intermediate of thelength of the latter. 7

Within the fractionating tower the low boiling fractions of the oil,together with the fixed pass upwardly through the tower, while theliquids, which accumulate in the bottom of said tower are drawn ofi' byway of pipe lines 11 and 12. The first of thwe lines extends to a hotoil pump 13 and the pi line 14, leaving the discharge side of this pumpleads to an intermediate heater or vaporizer 14' and thence to the oilline 3 of the inlet side of the converter. The excess oil, whichaccumulates in the bottom of the tower 9, is drawn off by way of thepipe line 12 in a heated state, usually at'a temperature ofapproximately 480 F. and use is made of this heated 011 to procurecertain heat economies ha'einafter specifically set forth.

The oil vapors or gases released from the top of the tower 9 pass by wayof a pipe line 15 to a water cooled condenser 16. where the condensiblematerials are reduced to liquid form and are discharged into a decanter17. In this decanter there takes place a separation of the gases, oiland water, the gases or non-condensibles being removed by of the outlet18 from the system, the water by way of the outlet 19 and the oil by wayof the pipe line 20. By this method of operationtheoiltobetreatedisfreefromextraneoua materials which do not requirecolor and gum removing treatment and the entire operation of the systemaccordingly is simplified and rendered more effective and economical.

The oil from the decanter is forced th rough the p1peline20bymeansofa p21 and in the line there is arrangeda texchanger ed by coming into 22.The pipe line 12 which conducts excess oil awa from the mouth of thetower 9, passes throug the exchanger 22 for the urpose of heating theoil pumped through t e line 20. Ordinarily, the oil in the line 12maintains an average temperature of approximately 480 F. and this hotoil is ut ized by the exchanger 22 to raise the temperature of the oilreleased from the decanter after such oil has passed through the pump21. .The pipe lme 12 after passingntgrough the heat exchanger 22, alsopasses t ugh a seco'nd exchanger 23. The exchanger 23 carries a bod ofwater which is reduced to superheate steam by the heat of the oilpassing through the line 12. The superheated steam may be introducedinto the system by way of the pipe line 4 at a point ahead of theconverter 1. After passing through the condenser 23 the oil passesthrough a water cooled coil 24 where its temperature is reduced toapproximately 100 C. and from the cooler 24 the oil p into a tank 25 andthence back to the storage tank 7 by way of the line 26.

The oil pumped through the pipe line 20, after it leaves the exchanger22, enters a fractionating column 27, the lower portion of which beingprovided with a hot oil reservoir 28 which is adapted to be heated, ifneca burner 29. That portion of the oil whi does not va rize within thereservoir 28, but remains in liquid form, is withdrawn by way of a pipeline 30 and removed from the system. The lighter or vaporized fractionsof the oil introduced into the fractionating column 27, pas overheadfrom the latter by way. of a pipe line 31 and while in a state of vaporare introduced into one of a plurality of fullers earth towers 32. Eachof these towers contain a bed of fullers earth or other equivalentmaterial, as indicated at 83, and the heated oil vapors, at atemperature of 425 F. circulate or pass through the filtering materialwhich, as is well known, operates in the ordinary manner to removeundesirable compounds from the oils. These undesirable compounds are inthe nature of polymers which tend to d scolor the final distillate or toproduce gum forming compounds therein which must be removed before thedistillate-is suitable for motor fuel purposu. The'heavy fractions orpolymers accumulate in liquid form in the bottoms of the towers 32 andare withdrawn by way of the pipe lines 34. The lighter or vaporousfractions, following filtration through the fullers earth bed, areremoved by way of the pipe line 35 and after pasing through-a smallfractionating tower 36 the vapors are led to a condenser 37 and reducedto liquid form and arethendischargedintoastorage tankas finished motorfuel.

From the foregoing, it will be seen that the present invention providesa system of oil treatment and fractionation by mealof which a desiredmotor fuel product may be obtained free fromundesirable compounds whichwould interfere with the value of such a product as a motor fueldistillate. By removing the water and non-condensibles from the motorfuel fractions the fullers earth or other treating apparatus is used inconnection with only that portion of the hydrocarbons originallyintroduced into the system, which have direct value as motor fuel. lhisgreatly increases the efficiency of the fullers earth towers or othertreating apparatus and permits a given body of fullers earth to beemployed efficiently for a longer period of time than has beenheretofore secured by the previous methods of passing all materialsthrough the fullers earth towers. Furthera more, the fullers earthoperates to better advantage at the higher oil temperatures whichobtains by the use of this system, since the mean temperature of the oilvapors when in contact with the treating materials is materially higherthan the corresponding temper atures of the intermingled fluidsheretofore employed. It will be understood that I do not limit myself tothe precise arrangements and steps of operation above specifically setforth, but reservethe rightto employ all such variations ormodifications of the invention that maybe said to fall fairly within thescope of the subjoined claim.

What is claimed is: In the treatment of hydrocarbon oils, the processwhich consists in subjecting a con-' fined stream of cracked oil vaporto fractionation to remove from such oil vapor compounds possessing anundesirably high boilmg range, subsequently condensing said vapors toproduce a condensate of low boiling 40 range, passing such condensate toa treating zone to effect the removal therefrom of undesirablegum-forming and color-imparting bodies, removing the oils of undesirablehigh boiling range from the fractionating zone in two streams, passingone of said streams through a conversion zone to subject saidlatter'oils to molecular decomposition,.intro- I ducing into the oilsdischarged from the converter a body of fresh oil obtained from a sourceof supply, passing such fresh oil together with the cracked oils to thefractionating zone, passing the other stream of high boihng oil from thefractionating zone through a series of heat exch rs and thence back tothe source offresh oil supply,

developing steam in one of said heat exchangers or introduction intotheoils passing to the conversion zone, and utilizing the other heatexchanger for preheating the condensate passing to the treating zone.

In'testimony whereof I aflix m s' ature. v

' CARY R. W AG R.

